This invention relates to a portable power tool having a rotation motor driving an output spindle via an angle drive located in an angle drive chamber partly filled with lubricating grease.
This type of tool is very common and is used for grinding tools, power nutrunners, boring machines etc. Either electrically or pneumatically powered these tools suffer from the problem of having a limited service life of the angle drive mainly due to poor lubrication. This problem is particularly significant at fast rotating tools like grinding tools.
The angle drive of such a power tool is lubricated by grease which is added to the angle drive chamber at the assembly of the tool and/or added at certain operation intervals. Grease fitted at the assembly of the tool will after a relatively short time of operation be thrown off the gear teeth and be deposited on the angle drive chamber walls. Also grease added at certain operation intervals will be thrown off the gear teeth after a relatively short time of tool operation. To ensure a satisfactory lubrication of the angle drive grease should have to be added at very short operation intervals, which would be a rather awkward and time consuming maintenance procedure. Besides, if too large an amount of grease were added to the angle drive chamber there would be an undesired heat development due to internal viscous friction in the grease. This means that you can add grease a few times only before the total amount of grease becomes too large.
Using oil instead of grease would perhaps improve lubrication of the angle drive, but would instead create a difficult seal problem to solve, namely how to safely keep the oil inside the angle drive chamber during a long enough tool operation time.
The main object of the invention is to accomplish a device for repeated redistribution of the grease once supplied to the angle drive chamber such that the grease will be repeatedly moved from those surfaces of the angle drive chamber where it tends to be deposited during operation of the tool toward the gear teeth of the angle drive.
Another object of the invention is to accomplish a device for repeated redistribution of grease which is compact and simple in design and which does not require redesign of a standard type angle drive housing.
Further objects and advantages of the invention will appear from the following specification and claims.
A preferred embodiment of the invention is described in detail below with reference to the accompanying drawings.